Kyushu University Academic Staff Educational and Research Activities Database
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TODA HIROYUKI Last modified date:2023.11.22

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Structural Materials research Lab. .
Academic Degree
Doctor of Engineering
Country of degree conferring institution (Overseas)
Field of Specialization
Strength of Materials, Mechanical Properties of Materials
Total Priod of education and research career in the foreign country
Outline Activities
I have lead a research group exploring materials strength and characterisation in 3D/4D. My research is in the field of deformation, fracture and fatigue on a wide range of structural/functional materials. A major focus is the exploration of the microstructure and the microstructure-property relations of such materials utilizing synchrotron X-ray microtomography at the third generation facilities, in particular the development of advanced 3D/4D measurements of stress/strain, crack-driving forces, chemical composition and crystallographic information in high density together with their applications to various issues in materials and mechanical engineerings. Recently we have proposed a new concept entitled "Reverse 4D Materials Engineering", in which the complex morphologies of existing materials is taken into account to realize a paradigm shift in materials development for structural/functional materials. We are also in charge of the development of new innovative aerospace materials that is based on a real fracture behavior that has been achiebved by applying the above-mentioned techniques.
Research Interests
  • 3D / 4D multi-scale / multi-modal materials science developed by ultra high resolution X-ray microscope
    keyword : Synchrotron radiation, Microtomography, Mechanical properties, Structural materials, Imaging CT, X-ray microscopy
  • Half-spontaneous interfacial debonding: Tomography bridging nano and macro scales
    keyword : Synchrotron radiation, Micro・nanotomography, Hydrogen embrittlement, Aluminum, First principles somulation, Hydrogen partitioning
  • 3D / 4D mesoscale materials science developed by ultrahigh magnification X-ray microscope
    keyword : Synchrotron radiation, Microtomography, Mechanical properties, Structural materials, Imaging CT, X-ray microscopy
  • Science of fatigue and fracture: Three-dimensional analyses of crack-tip using synchrotron radiation
    keyword : Synchrotron radiation, Microtomography, fatigue fracture, Tracking, Strain, Crack driving force, Mapping, Titanium alloys
  • Optimisation of microstructures in aluminium alloys via hydrogen partitioning control
    keyword : Synchrotron radiation, Microtomography, Mechanical properties, Hydrogen trapping, Hydrogen embrittlement, Pore, Tracking, Strain, Mapping, Aluminum alloys
  • Image-based analyses in 3D/4D and their application to structural materials
    keyword : Synchrotron radiation, Microtomography, Mechanical properties, Structural materials, Tracking, Strain, Chemical concentration, Crack driving force, Mapping, Steels, Aluminum alloys
  • Development of new innovative aerospace materials
    keyword : Synchrotron radiation, Microtomography, Mechanical properties, Structural materials, Hydrogen, Pore, 3D/4D analyses
  • A New Concept Breakthrough in Materials Development: Reverse 4D Materials Engineering
    keyword : Synchrotron radiation, Microtomography, Mechanical properties, Structural materials, Optimization, Coarsening, Image-based simulation
  • Crystallographic deformation behaviors of polycrystalline materials
    keyword : Synchrotron radiation, Microtomography, X-ray difffraction, Polycrystalline materials, Crystallographic orientation, Deformation, Fracture, Damage, Structural materials
Academic Activities
1. H. Toda, X-Ray CT: Hardware and Software Techniques, Springer Nature Singapore Pte Ltd., 2021.03, 医学用以外でX線CTに特化した専門書・テキストは、和書だけではなく海外の英書を見てもほとんど無く、あっても内容が薄かったり偏りのあるものである。著者がこれまで得てきた科研費基盤(S)1件、基盤(A)2件など、およびJSTやNEDO、内閣府などのナショナルプロジェクトの成果を全て網羅し、この分野で重要な知見を漏れなく紹介している。同時に、これを理解するのに必要な素養、知識、学術も合わせて網羅して体系的な専門書とすることで、この研究分野のバイブルとする事に成功した。この研究分野の多くの研究者、企業の技術者が手にしてこれを元に業務を推進しており、この分野にはなくてはならない成書となっている。科研費(研究成果公開促進)の学術図書部門で申請して採択された。これにより科研費の助成により英書が海外の出版社(Springer社)から出版された。国内外で次世代への当該先端技術の普及と継承、国際的な研究分野の先導などがなされることになる。.
2. Y. Suzuki, H. Toda, "Tomography using magnifying optics", Advanced Tomographic Methods in Materials Research and Engineering, Section 7.1 "Fresnel zone-plate microscopy and microtomography" in Chapter 7, Oxford University Press, 2008.03.
1. Tomography for Bridging Nano and Macro: Semi-spontaneous Iinterfacial Debonding.
1. H.Toda, K. Hirayama, K. Okamura, T. Suzuki, A. Takeuchi, M. Uesugi, H. Fujihara, Multimodal assessment of mechanically induced transformation in metastable multi‐phase steel using X‐ray nano‐tomography and pencil‐beam diffraction tomography, Acta Materialia, 10.1016/j.actamat.2022.117956, 234, 117956, 2022.08, A combination of X-ray nano-tomography and pencil-beam diffraction tomography was utilized for multimodal assessment of the mechanically induced transformation of individual retained austenite grains during tensile deformation in a 0.1C-5Mn-1Si multi-phase steel. In the present study, a newly developed high energy (20 - 30 keV) and high resolution (spatial resolution of 0.16 µm in this study) X-ray nano-tomography technique was applied for the first time to the in-situ observation of a steel under external loading. The gradual transformation, plastic deformation, and rotation behaviour of the individual austenite grains were clearly observed in 3D. It was revealed that the early stage of the transformation was dominated by the stress-assisted transformation that can be associated with measured mechanical driving force, whilst the overall transformation was dominated by the strain-induced transformation that is interrelated with measured dislocation multiplication. The transformation behaviour of individual grains was classified according to their initial crystallographic orientation and size. Noteworthy was the high stability of coarse austenite grains (i.e., 2.5 μm or larger in diameter), contrary to past reports in the literature. Characteristic rotation behaviour and wide data dispersion were also observed in the case of the individual austenite grains. It was conclusively demonstrated that such characteristic behaviour partly originated from interactions with surrounding soft and hard phases. The origins of these characteristics are discussed by combining the image-based and diffraction-based information..
2. Y. Wang, B. Sharma, Y. Xu, K. Shimizu, H. Fujihara, K. Hirayama, A. Takeuchi, M. Uesugi, G. Cheng, H. Toda, Switching nanoprecipitates to resist hydrogen embrittlement in high-strength aluminum alloys, Nature Communications, 10.1038/s41467-022-34628-4, 13, 1, 6860, 2022.11, Hydrogen drastically embrittles high-strength aluminum alloys, which impedes efforts to develop ultrastrong components in the aerospace and transportation industries. Understanding and utilizing the interaction of hydrogen with core strengthening elements in aluminum alloys, particularly nanoprecipitates, are critical to break this bottleneck. Herein, we show that hydrogen embrittlement of aluminum alloys can be largely suppressed by switching nanoprecipitates from the η phase to the T phase without changing the overall chemical composition. The T phase strongly traps hydrogen and resists hydrogen-assisted crack growth, with a more than 60% reduction in the areal fractions of cracks. The T phase-induced reduction in the concentration of hydrogen at defects and interfaces, which facilitates crack growth, primarily contributes to the suppressed hydrogen embrittlement. Transforming precipitates into strong hydrogen traps is proven to be a potential mitigation strategy for hydrogen embrittlement in aluminum alloys..
3. Y. Wang, H. Toda, Y. Xu, K. Shimizu, K. Hirayama, H. Fujihara, A. Takeuchi, M. Uesugi, In-situ 3D observation of hydrogen-assisted particle damage behavior in 7075 Al alloy by synchrotron X-ray tomography, Acta Materialia, 10.1016/j.actamat.2022.117658, 227, 117658, 2022.02, Al-Zn-Mg合金でZn量を10%まで増やした新奇高強度合金を作製し、その水素脆化挙動をシンクロトロン放射光を用いた超高分解能3D連続観察で明らかにした。この合金の水素脆化挙動を解明すると共に、その防止策も提案した。.
4. Y. Xu, H. Toda, K. Shimizu, Y. Wang, B. Gault, W. Li, K. Hirayama, H. Fujihara, X. Jin, A. Takeuchi, M. Uesugi, Suppressed hydrogen embrittlement of high-strength Al alloys by Mn-rich intermetallic compound particles, Acta Materialia, 10.1016/j.actamat.2022.118110, 236, 118110, 2022.09, The pursuit of strong and ductile Al alloys with superior resistance to hydrogen embrittlement (HE) is practically significant across the aerospace and transportation industries among others. Unfortunately, effective ways to progress on the strength-HE trade-off for Al-alloys remain elusive. A strategy of suppressing HE by introducing intermetallic compound (IMC) particles to achieve hydrogen redistribution in various trapping sites was proposed. Here, we systematically induce the precipitation of a constant volume fraction of intermetallic compound (IMC) particles by adding one of 14 elements in a ternary Al-Zn-Mg high-strength alloy. We show a strong correlation between hydrogen trapping energies of the IMC obtained from ab initio calculations with the resistance to HE. Mn-rich Al11Mn3Zn2 particles exhibit the highest hydrogen trapping energy (0.859 eV/atom), leading to a decrease by approximately 5 orders of magnitude in the hydrogen occupancy in η2 (MgZn2) phase interfaces and grain boundaries, where HE cracks initiate. The Mn-addition did not deteriorate the ductility and most Al11Mn3Zn2 particles remained intact during plastic deformation which was revealed by in-situ 3D X-ray tomography. Hydrogen-induced strain localization at η2 phase interfaces and grain boundaries were inhibited due to strong hydrogen trapping capacity of Al11Mn3Zn2, hence preventing HE cracks initiation. Our approach effectively suppresses hydrogen-induced cracks without sacrificing the ductility, and our strategy can help the design roadmap of HE-tolerant high-strength metallic alloys..
5. K. Hirayama, H. Toda, D. Fu, R. Masunaga, H. Su, K. Shimizu, A. Takeuchi and M. Uesugi, Damage micromechanisms of stress corrosion cracking in Al-Mg alloy with high magnesium content, Corrosion Science, 10.1016/j.corsci.2021.109343, 184, 109343, 2021.05, Al-Mg合金でMg量を10%まで増やした新奇高強度合金を作製し、その応力腐食割れ挙動をシンクロトロン放射光を用いた超高分解能3D連続観察で明らかにした。この合金の応力腐食割れ挙動を解明すると共に、その防止策も提案した。.
6. T. Tsuru, K. Shimizu, M. Yamaguchi, M. Itakura, K. Ebihara, A. Bendo, K. Matsuda, H. Toda, Hydrogen-accelerated spontaneous microcracking in high-strength aluminium alloys, Scientific Reports, 10.1038/s41598-020-58834-6, 10, 1, 1998-1998, 2020.04.
7. Hiroyuki Toda, Takanobu Kamiko, Yasuto Tanabe, Masakazu Kobayashi, D. J. Leclere, Kentaro Uesugi, Akihisa Takeuchi, Kyosuke Hirayama, Diffraction-amalgamated grain boundary tracking for mapping 3D crystallographic orientation and strain fields during plastic deformation, ACTA MATERIALIA, 10.1016/j.actamat.2016.01.072, 107, -, 310-324, 2016.04, By amalgamating the X-ray diffraction technique with the grain boundary tracking technique, a novel method, diffraction-amalgamated grain boundary tracking (DAGT), has been developed. DAGT is a non-destructive in-situ analysis technique for characterising bulk materials, which can be applied up to near the point of fracture. It provides information about local crystal orientations and detailed grain morphologies in three dimensions, together with high-density strain mapping inside grains. As it obtains the grain morphologies by utilising X-ray imaging instead of X-ray diffraction, which latter is typically vulnerable to plastic deformation, DAGT is a fairly robust technique for analysing plastically deforming materials. Texture evolution and localised deformation behaviours have here been successfully characterised in Al-Cu alloys, during tensile deformation of 27% in applied strain. The characteristic rotation behaviours of grains were identified, and attributed to the effects of interaction with adjacent grains on the basis of the 3D local orientation and plastic strain distributions. It has also been revealed that 3D strain distribution in grains is highly heterogeneous, which is not explained by known mechanisms such as simple incompatibility with adjacent grains or strain percolation through soft grains. It has been clarified that groups consisting of a few adjacent grains may deform coordinately, especially in shear and lateral deformation, and the characteristic deformation pattern is thereby formed on a mesoscopic scale. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved..
8. Hiroyuki Toda, Akihide Takijiri, Masafumi Azuma, Shohei Yabu, Kunio Hayashi, Dowon Seo, Masakazu Kobayashi, Kyosuke Hirayama, Akihisa Takeuchi, Kentaro Uesugi, Damage micromechanisms in dual-phase steel investigated with combined phase- and absorption-contrast tomography, ACTA MATERIALIA, 10.1016/j.actamat.2017.01.010, 126, 401-412, 2017.03, The single-distance phase retrieval technique was applied to contrast-enhanced imaging of the dual phase microstructure of a ferrite/martensite dual-phase with only 1.4% difference in density between the two phases. Each high-resolution absorption-contrast image was registered with a corresponding phase-contrast image, to analyse damage evolution behaviour. The loading step at which each microvoid was nucleated was identified by tracking the microvoid throughout tension, together with its nucleation site. Premature damage initiation was observed at a relatively early stage at various nucleation sites, such as the ferrite interior, martensitic interior and ferrite/martensite interfaces; however, the subsequent growth of such microvoids was relatively moderate. On the other hand, microvoids were also initiated later due to martensitic cracking after the maximum load was reached, and these microvoids subsequently exhibited rapid growth. The martensite cracking induced additional damage evolution mainly along nearby ferrite/martensite interfaces and intersections between the martensite and the ferrite grain boundary. It is notable that the microvoids originating from martensitic cracking exhibited characteristic shear-dominated growth under macroscopic tension, whereas those originating from the other nucleation sites exhibited traditional triaxiality-dominated growth. It was concluded that the ductile fracture was dominated by the substantial force driving the growth of microvoids located on morphologically characteristic martensitic particles. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd..
9. H. Su, H. Toda, K. Shimizu, K. Uesugi, A. Takeuchi, Y. Watanabe, Assessment of hydrogen embrittlement via image-based techniques in Al-Zn-Mg-Cu aluminum alloys, Acta Materialia, 10.1016/j.actamat.2019.06.056, 176, 96-108, 2019.09.
10. H. Li, H. Toda, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, Application of diffraction-amalgamated grain boundary tracking to fatigue crack propagation behavior in high strength aluminum alloy, Materials Transactions, 10.2320/matertrans.M2014340, 56, 3, 424-428, 2015.03.
11. H. Toda, I. Sinclair, J.-Y. Buffiere, E.Maire, T. Connolley, M. Joyce, K.H. Khor, P. Gregson, Assessment of fatigue crack closure phenomenon in damage tolerant aluminium alloy by in-situ high-resolution synchrotron X-ray microtomography, Philosophical Magazine A, 83, 21, 2429-2448, 2003.07.
12. H. Toda, J. Katano, T. Kobayashi, T. Akahori, M. Niinomi, Assessment of thermo-mechanical fatigue behaviors of cast Al-Si alloys by experiments and multi-step numerical simulation, Materials Transactions, 46, 1, 111-117, 2005.01.
13. L. Qian, H. Toda, K. Uesugi, T. Kobayashi, T. Ohgaki, M. Kobayashi, Application of synchrotron x-ray microtomography to investigate ductile fracture in Al alloys, Applied Physics Letters, 10.1063/1.214208, 87, 24, 241907, 2005.12.
14. L. Li, H. Toda, T. Ohgaki, M. Kobayashi, T. Kobayashi, K. Uesugi, Y. Suzuki, Wavelet-based local region-of-interest reconstruction for synchrotron radiation X-ray microtomography, Journal of Applied Physics, 102, 114908-1-9, 2007.01.
15. L. Qian, H. Toda, K. Uesugi, M. Kobayashi, T. Kobayashi, Direct observation and image-based simulation of three-dimensional tortuous crack evolution inside opaque materials, Physical Review Letters, 100, 11, 115505, 2008.11.
16. H. Toda, Y. Ohkawa, T. Kamiko, T. Naganuma, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, Grain boundary tracking technique: four-dimensional visualisation technique for determining grain boundary geometry with local strain mapping, Acta Materialia, 61, 14, 5535-5548, 2013.08, SPring-8を利用したX線CTを用いれば、結晶粒界にある粒子が鮮明に3D観察できることに着目した。このような粒子は、金属が変形し、破壊していく過程でも常に結晶粒界に位置する為、結晶粒界の粒子の情報を使えば、個々の結晶の形を4Dで求めることができると発想した。2011年度には、この手法を実用的な構造材料に適用できるレベルにまで高精度化することに成功した。この手法により、多結晶材料中のすべての結晶粒の形状の変化を時間を遡りながら4Dで観察することができるようになった。この成果は、金属材料工学では最も権威のある英文誌であるアクタ・マテリアリア誌に掲載が決定された。.
17. H. Toda, K. Tsubone, K. Shimizu, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Nakazawa, Y. Aokic, M. Kobayashi, Compression and recovery micro-mechanisms in flexible graphite, Carbon, 59, 184-191, 2013.08.
1. H. Toda, M. Yamaguchi, T. Tsuru, K. Shimizu, H. Fujihara, K. Hirayama, K. Ebihara, K. Matsuda, Hydrogen embrittlement in Al-Zn-Mg alloys: Semi-spontaneous interfacial decohesion of precipitates, ICAA18(The 18th International Conference on Aluminium Alloys), 2022.09.
2. H. Toda, M. Yamaguchi, T. Tsuru, K. Shimizu, K. Hirayama, K. Ebihara, K. Matsuda, Hydrogen embrittlement mechanism of Al-Zn-Mg alloys: semi-spontaneous interfacial decohesion, MRM2021 (Materials Research Meeting 2021), 2021.12, [URL].
3. H. Toda, K. Hirayama, K. Shimizu, K. Uesugi, A. Tkauchi, Application of high-resolution X-ray tomography to hydrogen embrittlement in aluminium, ICAA17 (The 17th International Conference on Aluminium Alloys), 2020.10.
4. H. Toda, K, Hirayama, H. Su, K. Shimizu, O. Takakuwa, A. Takeuchi, K. Uesugi, Recent progress in high resolution X-ray tomography at high X-ray energies, PRICM 10(The 10th Pacific Rim International Conference on Advanced Materials and Processing), 2019.08.
5. H. Toda, H. Su, K. Shimizu, H. Fujihara, K. Hirayama, A. Takeuchi, K. Uesugi, Assessment of hydrogen embrittlement via in-situ imaging techniques in high Zn Al-Zn-Mg alloys, ECF22(22nd European Conference on Fracture), 2018.08.
6. H. Toda, K. Hirayama, K. Shimizu, K. Uesugi, Application of high-resolution X-ray tomography to hydrogen embrittlement in aluminium, THERMEC'2018, 2018.07.
7. H. Toda, K. Shimizu, H. Gao, K. Hirayama, 4D hydrogen embrittlement behaviour in high strength aluminium alloy, TMS 2018 Annual Meeting & Exhibition, 2018.03.
8. H. Toda, K. Hirayama, M. Kobayashi, A. Takeuchi, K. Uesugi, Assessment of damage behavior of aluminum using diffraction-amalgamated grain boundary tracking technique, 2017 MRS Fall meeting, 2017.01.
9. H. Toda, M. Kobayashi , K. Hirayama, Application of diffraction-amalgamated grain-boundary tracking to deforming aluminium polycrystals, THERMEC 2016, 2016.05.
10. H. Toda, Origin of ductile fracture in aluminium alloys, IUTAM Symposium on Plastic localization and ductile failure, 2015.03.
11. H. Toda, M. Kobayashi, R. Batres, K. Shimizu, O. Kuwazuru, A new concept breakthrough in materials development: reverse 4D materials engineering, Proceedings of the 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2012.11, シンクロトロン放射光を用い て得た膨大な4D画像を『粗視化』し、簡単な幾何学パラメーターで現象を説明すること、およ び得られた4D画像を用いて行うイメージベースシミュレーションによるミクロ組織最適化の 二つを組み合わせ、「リバース4D材料エンジ ニアリング」なる材料開発プロセスの構想を得た。この基調講演では、その内容に関して講演した。この手法を用いれば、従来の「設計→試作 →製品」とは逆の、「設計←評価・解析←製品」という流れ(『リバース』というゆえん)により、「試作⇔評価」といった時間とコストのか かるプロセスを経ずに、高能率、短時間、高精度で構造材料設計が可能になる。.
12. H. Toda, D. J. LeClere, T. Kamiko, Y. Suzuki, A. Takeuchi, K. Uesugi, M. Kobayashi, Development of diffraction-amalgamated grain-boundary tracking technique and its application to polycrystalline metals, Proceedings of SPIE, 2012.08, 我々は、シンクロトロン放射光を用いて得た3D/4D画像の内部に多数のミクロ構造が見えることを利用し、各画像間でミクロ組織特徴点(粒子など)を高精度に追跡する技術(ミクロ組織追跡法)を発案して開発した。その後、これを応用し、結晶粒の3D/4D観察を行うことができる結晶粒界追跡法、さらにこれに結晶方位マッピングを加えたX線回折援用結晶粒界追跡法を相次いで提案し、実現している。機械材料の変形・破壊の評価では、SEM-EBSP(電子線後方散乱回折)法や各種TEM(透過型電子顕微鏡)観察が多用される。発表手法は、これら2D(二次元)情報を3D/4Dに拡張できる、唯一かつオリジナルな技法である。.
Membership in Academic Society
  • The Japan Institute of Light Metals
  • Japan Foundry Engineering Society
  • The Iron and Steel Institute of Japan
  • The Japan Institute of Metals and Materials
  • The Japan Society of Mechanical Engineers
  • The Society of Materials Science
  • JSPS 147th Committee
  • JSPS 176th Committee
  • SPring-8 users community
  • SPring-8 X-ray Micro/Nano-tomography Research Group
Educational Activities
I am teaching three courses on "Strength of Materials" in the bachelor course, which cover basic theories of strength of materials. I am also in charge of student experiments (mechanical testing). In the graduate school, I am teaching a course entitled "Evaluation of structural materials", "Strength of automobiles" and Introduction to automotive science". I also supervise several graduate students, several bachelor students and some pos-docs in the laboratory.